Direct and indirect reciprocity among individuals and groups

Free mobility across group boundaries promotes intergroup cooperation

Group cooperation is a cornerstone of human society, enabling achievements that surpass individual capabilities. However, groups also define and restrict who benefits from cooperative actions and who does not, raising the question of how to foster cooperation across group boundaries. This study investigates the impact of voluntary mobility across group boundaries on intergroup cooperation. Participants, organized into two groups, decided whether to create benefits for themselves, group members, or everyone. In each round, they were paired with another participant and could reward the other's actions during an 'enforcement stage', allowing for indirect reciprocity. In line with our preregistered hypothesis, when participants interacted only with in-group members, indirect reciprocity enforced group cooperation, while intergroup cooperation declined. Conversely, higher intergroup cooperation emerged when participants were forced to interact solely with out-group members. Crucially, in the free-mobility treatment - where participants could choose whether to meet an in-group or an out-group member in the enforcement stage - intergroup cooperation was significantly higher than when participants were forced to interact only with in-group members, even though most participants endogenously chose to interact with in-group members. A few 'mobile individuals' were sufficient to enforce intergroup cooperation by selectively choosing out-group members, enabling indirect reciprocity to transcend group boundaries. These findings highlight the importance of free intergroup mobility for overcoming the limitations of group cooperation.

Nasty and Noble Notes: Interdependence Structures Drive Self-Serving Gossip

Much information people receive about others reaches them via gossip. But is this gossip trustworthy? We examined this in a scenario study (Nsenders = 350, Nobservations = 700) and an interactive laboratory experiment (Nsenders = 126; Nobservations = 3024). In both studies, participants played a sequential prisoner's dilemma where a gossip sender observed a target's (first decider's) decision and could gossip about this to a receiver (second decider). We manipulated the interdependence structure such that gossipers' outcomes were equal to targets' outcomes, equal to receivers' outcomes, or independent. Compared to no interdependence, gossip was more often false when gossipers were interdependent with targets but not when interdependent with receivers. As such, false positive gossip (self-serving when interdependent with targets) increased but false negative gossip (self-serving when interdependent with receivers) did not. In conclusion, the interdependence structure affected gossip's trustworthiness: When gossipers' outcomes were interdependent with targets, gossip was less trustworthy.

The development of cooperation and cooperative norm enforcement in children and adolescents: The role of in-group favoritism

Various scholars have discussed the influence of group membership on cooperative behaviors in adult samples. Nonetheless, the developmental trajectories of related biases from middle childhood and early adolescence remain to be explored. Using the one-shot 4-player public goods game and inducing group membership awareness by school affiliation, we investigated the effects of group membership of imaginary partners on cooperation (Experiment 1) and cooperative norm enforcement (Experiment 2) in children and adolescents across fourth (N = 106, Mage = 9.53 years, 57 girls), sixth (N = 109, Mage = 11.46 years, 54 girls) and eighth grades (N = 102, Mage = 13.22 years, 47 girls). In Experiment 1, participants were first-party players and showed higher cooperation with in-group members (i.e., players from the same school) than out-group members (i.e., from other schools); the mediating role of cooperative expectations in in-group favoritism in cooperation was observed only among fourth and sixth graders. In Experiment 2, participants were third-party executors (i.e., could punish either in-group and out-group free-riders), and results showed that fourth and sixth graders were more lenient with in-group violators; eighth graders showed no evident bias in punishment. These findings depict a developmental pattern of decline in in-group favoritism regarding cooperation and cooperative norm enforcement from middle childhood to early adolescence. Cooperative expectations mediated the effect of group membership on cooperation only among younger students, indicating that divergent mechanisms underlie cooperative bias between groups in different grades. The discussions suggest that the understanding of norms of both cooperation and equality developed during this period.

Cooperation and social organization depend on weighing private and public reputations

To avoid exploitation by defectors, people can use past experiences with others when deciding to cooperate or not ('private information'). Alternatively, people can derive others' reputation from 'public' information provided by individuals within the social network. However, public information may be aligned or misaligned with one's own private experiences and different individuals, such as 'friends' and 'enemies', may have different opinions about the reputation of others. Using evolutionary agent-based simulations, we examine how cooperation and social organization is shaped when agents (1) prioritize private or public information about others' reputation, and (2) integrate others' opinions using a friend-focused or a friend-and-enemy focused heuristic (relying on reputation information from only friends or also enemies, respectively). When agents prioritize public information and rely on friend-and-enemy heuristics, we observe polarization cycles marked by high cooperation, invasion by defectors, and subsequent population fragmentation. Prioritizing private information diminishes polarization and defector invasions, but also results in limited cooperation. Only when using friend-focused heuristics and following past experiences or the recommendation of friends create prosperous and stable populations based on cooperation. These results show how combining one's own experiences and the opinions of friends can lead to stable and large-scale cooperation and highlight the important role of following the advice of friends in the evolution of group cooperation.

Using artificial agents to nudge outgroup altruism and reduce ingroup favoritism in human-agent interaction

Ingroup favoritism and intergroup discrimination can be mutually reinforcing during social interaction, threatening intergroup cooperation and the sustainability of societies. In two studies (N = 880), we investigated whether promoting prosocial outgroup altruism would weaken the ingroup favoritism cycle of influence. Using novel methods of human-agent interaction via a computer-mediated experimental platform, we introduced outgroup altruism by (i) nonadaptive artificial agents with preprogrammed outgroup altruistic behavior (Study 1; N = 400) and (ii) adaptive artificial agents whose altruistic behavior was informed by the prediction of a machine learning algorithm (Study 2; N = 480). A rating task ensured that the observed behavior did not result from the participant's awareness of the artificial agents. In Study 1, nonadaptive agents prompted ingroup members to withhold cooperation from ingroup agents and reinforced ingroup favoritism among humans. In Study 2, adaptive agents were able to weaken ingroup favoritism over time by maintaining a good reputation with both the ingroup and outgroup members, who perceived agents as being fairer than humans and rated agents as more human than humans. We conclude that a good reputation of the individual exhibiting outgroup altruism is necessary to weaken ingroup favoritism and improve intergroup cooperation. Thus, reputation is important for designing nudge agents.

Understanding the cognitive and neuroimaging bases underlying the detrimental impact of sleep deprivation on reciprocity

Although the impact of sleep loss on social behaviors has been widely observed in recent years, the mechanisms underpinning these impacts remain unclear. In this study, we explored the detrimental effects of sleep deprivation on reciprocity behavior as well as its underlying psychological and neuroimaging mechanisms by combining sleep manipulation, an interpersonal interactive game, computational modeling and neuroimaging. Our results suggested that after sleep deprivation, individuals showed reduced reciprocity behavior, mainly due to their reduced weights on communal concern when making social decisions. At neural level, we demonstrated that sleep deprivation's effects were observed in the precuneus (hyperactivity) and temporoparietal junction, dorsal lateral prefrontal cortex (DLPFC) (both hypoactivity), and reduced reciprocity was also accounted for by increased precuneus-thalamus connectivity and DLPFC-thalamus connectivity. Our findings contributed to the understanding of the psychological and neuroimaging bases underlying the deleterious impact of sleep deprivation on social behaviors.

Group Formation and the Evolution of Human Social Organization

Humans operate in groups that are oftentimes nested in multilayered collectives such as work units within departments and companies, neighborhoods within cities, and regions within nation states. With psychological science mostly focusing on proximate reasons for individuals to join existing groups and how existing groups function, we still poorly understand why groups form ex nihilo, how groups evolve into complex multilayered social structures, and what explains fission-fusion dynamics. Here we address group formation and the evolution of social organization at both the proximate and ultimate level of analysis. Building on models of fitness interdependence and cooperation, we propose that socioecologies can create positive interdependencies among strangers and pave the way for the formation of stable coalitions and groups through reciprocity and reputation-based partner selection. Such groups are marked by in-group bounded, parochial cooperation together with an array of social institutions for managing the commons, allowing groups to scale in size and complexity while avoiding the breakdown of cooperation. Our analysis reveals how distinct group cultures can endogenously emerge from reciprocal cooperation, shows that social identification and group commitment are likely consequences rather than causes of group cooperation, and explains when intergroup relations gravitate toward peaceful coexistence, integration, or conflict.

Bidirectional Relationship between Adolescent Gender Egalitarianism and Prosocial Behavior

This study investigates the bidirectional associations between gender egalitarianism and prosocial behavior in adolescents, and the moderating effect of gender in the associations, as well as gender differences and longitudinal changes in both. We recruited 543 Chinese adolescents (284 girls, 259 boys; mean age at Time 1 = 11.27 years) and collected three waves of data measuring gender egalitarianism and prosocial behavior at one-year intervals. According to the results, girls expressed greater gender egalitarianism than boys did; girls reported more prosocial behavior than boys in the sixth grade, but there were no significant gender differences in the seventh and eighth grades. Adolescents' gender egalitarianism stayed stable from the sixth to the seventh grade then increased from the seventh to the eighth grade, and there was a decrease in prosocial behavior from the sixth to the seventh grade. More importantly, the results of the multi-group cross-lagged panel model revealed that adolescents' gender egalitarianism in the previous year positively predicted prosocial behavior in the next year, and vice versa; such bidirectional associations equally applied to boys and girls. These findings add to the knowledge of adolescent gender egalitarianism and prosocial behavior, and the dynamic interplay between the two.

Social Expectations are Primarily Rooted in Reciprocity: An Investigation of Fairness, Cooperation, and Trustworthiness

Social expectations guide people's evaluations of others' behaviors, but the origins of these expectations remain unclear. It is traditionally thought that people's expectations depend on their past observations of others' behavior, and people harshly judge atypical behavior. Here, we considered that social expectations are also influenced by a drive for reciprocity, and people evaluate others' actions by reflecting on their own decisions. To compare these views, we performed four studies. Study 1 used an Ultimatum Game task where participants alternated Responder and Proposer roles. Modeling participants' expectations suggested they evaluated the fairness of received offers via comparisons to their own offers. Study 2 replicated these findings and showed that observing selfish behavior (lowball offers) only promoted acceptance of selfishness if observers started acting selfishly themselves. Study 3 generalized the findings, demonstrating that they also arise in the Public Goods Game, emerge cross-culturally, and apply to antisocial punishment whereby selfish players punish generosity. Finally, Study 4 introduced the Trust Game and showed that participants trusted players who reciprocated their behavior, even if it was selfish, as much as they trusted generous players. Overall, this research shows that social expectations and evaluations are rooted in drives for reciprocity. This carries theoretical implications, speaking to a parallel in the mechanisms driving both decision-making and social evaluations, along with practical importance for understanding and promoting cooperation.

Do you reap what you sow? Driving mechanism of supply chain transparency on consumers' indirect reciprocity

Introduction

To maintain sustainable poverty alleviation in the post-pandemic world, China encourages firms to participate in the "Social Commerce Helping Farmers Project." This study aims to explore the phenomenon of indirect reciprocity between firms, consumers, and farmers in the supply chain. This study explores how supply chain transparency stimulates indirect reciprocity among consumers through competence trust, goodwill trust, and integrity trust. Furthermore, we explore the impact of compassion and the need for social status on the model.

Methods

We fit a partial least square analysis structural equation modeling (PLS-SEM) using data from an online random vignette-based experiment questionnaire survey.

Results

Supply chain transparency of social responsibility practices asymmetrically affects three dimensions of consumer trust by improving perceived information quality. And the three dimensions of trust asymmetrically contribute to indirect reciprocity. Furthermore, compassion has a positive moderating effect on the relationship between perceived information quality and trust. However, the moderating effect of the need for social status on the relationship between the three dimensions of trust and indirect reciprocity differed significantly.

Discussion

Our findings indicate that supply chain transparency improves consumer trust, making consumers more responsive and rewarding companies that assist vulnerable groups in their supply chains. Faced with a trust crisis, companies can take different measures to achieve their goals based on each dimension of trust. At the same time, companies need to consider differences in the responses of consumers with different personality traits (e.g., compassion and the need for social status) when revealing their corporate social responsibility practices to consumers.

The impact of social comparison and (un)fairness on upstream indirect reciprocity: Evidence from ERP

Event-related potential (ERP) technology and the dictator game paradigm are used to explore the formation mechanism of upstream indirect reciprocity behaviors. We design a within subject experiment of 3 (social comparison: upward versus parallel versus downward) × 2 (treatment: fair versus unfair) involving 49 subjects. In the first round of allocations, subjects are forced to accept a monetary amount allocated to them by another player. In the second round, subjects assume the role of allocator and divide a monetary amount between themselves and a third party. Our results show the following: 1) Having received fair treatment from someone else, individuals engaged in downward comparison are more inclined to reciprocate the fairness they had received to a third party compared to individuals in parallel and upward comparison conditions. If individuals receive unfair treatment, they tend to repeat this behavior to a third party regardless of which social comparison condition they are in; 2) Under the condition of upward comparison, individuals receiving unfair treatment exhibit greater FRN amplitude and less P300 amplitude, but in parallel and downward comparison conditions, there is no significance in FRN and P300 amplitude between individuals receiving fair and unfair treatment.

The marmoset as a model for investigating the neural basis of social cognition in health and disease

Social-cognitive processes facilitate the use of environmental cues to understand others, and to be understood by others. Animal models provide vital insights into the neural underpinning of social behaviours. To understand social cognition at even deeper behavioural, cognitive, neural, and molecular levels, we need to develop more representative study models, which allow testing of novel hypotheses using human-relevant cognitive tasks. Due to their cooperative breeding system and relatively small size, common marmosets (Callithrix jacchus) offer a promising translational model for such endeavours. In addition to having social behavioural patterns and group dynamics analogous to those of humans, marmosets have cortical brain areas relevant for the mechanistic analysis of human social cognition, albeit in simplified form. Thus, they are likely suitable animal models for deciphering the physiological processes, connectivity and molecular mechanisms supporting advanced cognitive functions. Here, we review findings emerging from marmoset social and behavioural studies, which have already provided significant insights into executive, motivational, social, and emotional dysfunction associated with neurological and psychiatric disorders.